Scotland Yard's race row deepened on Thursday as three officers were referred to the police watchdog over comments to colleagues.
Two PCs and an acting sergeant have been put on restricted duties after complaints about their conduct between January and March.
The fresh allegations come after Commissioner Bernard Hogan-Howe vowed to get to the bottom of "very damaging" footage of an officer apparently racially abusing a man and another allegedly assaulting a teenage boy last summer.
The officers based in Newham were reported to the Metropolitan Police's Directorate of Professional Standards (DPS) on 19 March - before separate allegations of racism in the wake of last summer's riots became public.
Commander Peter Spindler said: "These are serious allegations that are being thoroughly investigated so that robust action can be taken if proven.
"The Commissioner has already stated there is no place for racist behaviour in the MPS and we will work with the IPCC to identify any wrongdoing."
The complaint was made to the force's internal conduct body before Mr Hogan-Howe said: "I will not stand for any racism or racists".
The police chief had been forced to speak out after incidents on 11 August last year as police officers in London dealt with the fallout of the riots sweeping the capital.
The arrested man, named as Mauro Demetrio, 21, from Beckton, east London, was arrested on suspicion of drug driving but no action was later taken. He recorded the abuse on his mobile phone.
It also emerged that another officer, reportedly with PC MacFarlane when Mr Demetrio was abused, was placed on restricted duties after later being allegedly seen kicking the 15-year-old black boy to the ground and kneeing him.
The incident was said to have happened in the custody area of an east London police station with part of the incident recorded on CCTV.
"Unfortunately just one alleged incident like this can be very damaging to public confidence," Mr Hogan-Howe told staff earlier this week.
"This is a great organisation - one we should all be proud to work for. Without pre-judging this case, in any instance of wrongdoing it is a small few who tarnish the vast majority.
"What we have heard over the last few days is of course completely at odds with all the close work that goes on with communities across London every day. We work hard to forge strong relationships with people who can advise us and rightly hold us to account.
"I want us all to go out there and remind those communities of our commitment to fairness and professionalism.
"We have a duty to challenge or report any behaviour by colleagues which is less than the high standard demanded by the service and Londoners themselves.
"You cannot avoid that duty. Nor can I.
"I will not stand for any racism or racists in the Met."